The present invention relates to a condenser used in a car air conditioner which is a refrigeration cycle mounted on, for example, an automobile.
Herein and appended claims, the upper side and lower side of FIG. 1 will be referred to as “upper” and “lower,” respectively.
Herein, the term “liquid-phase refrigerant” encompasses liquid-phase predominant mixed-phase refrigerant containing a small amount of gas-phase refrigerant.
The applicant of the present invention has proposed a condenser for a car air conditioner (see Japanese Patent Application Laid-Open (kokai) No. 2010-185648). The proposed condenser includes a condensation section, a supercooling section provided below the condensation section, and a liquid receiver which is provided between the condensation section and the supercooling section and which receives gas-liquid-mixed-phase refrigerant from the condensation section and separates the gas-liquid-mixed-phase refrigerant into gas-phase refrigerant and liquid-phase refrigerant. The condensation section includes a condensation section outlet header whose longitudinal direction coincides with a vertical direction, and a plurality of heat exchange tubes each of which is connected, at one end in the longitudinal direction, to the condensation section outlet header. The supercooling section includes a supercooling section inlet header disposed below the condensation section outlet header such that its longitudinal direction coincides with the vertical direction, and a plurality of heat exchange tubes each of which is connected, at one end in the longitudinal direction, to the supercooling section inlet header. The liquid receiver is composed of a tubular base member having an open upper end and a closed lower end, and a cylindrical tubular liquid receiver main body which has a closed upper end and an open lower end and which is screwed into the base member. A refrigerant inflow hole into which refrigerant flows from the condensation section outlet header of the condensation section and a refrigerant outflow hole from which refrigerant flows into the supercooling section inlet header of the supercooling section are formed in the base member such that the refrigerant inflow hole is spaced from the refrigerant outflow hole in the vertical direction and is located above the refrigerant outflow hole. A plate-shaped partition member for dividing the interior of the liquid receiver into upper and lower compartments is provided in the base member at a vertical position between the refrigerant inflow hole and the refrigerant outflow hole. An overflow pipe is provided on the partition member which allows refrigerant to flow from the first compartment above the partition member to the second compartment below the partition member when the level of refrigerant within the first compartment reaches a predetermined level. The upper end of the overflow pipe is located at a vertical position above the refrigerant inflow hole, and the cross-sectional area of the flow passage of the overflow pipe is approximately the same as the hole area of the refrigerant inflow hole.
In the condenser disclosed in the publication, the gas-liquid-mixed-phase refrigerant having flowed from the condensation section outlet header into the first compartment within the liquid receiver through the refrigerant inflow hole is separated into gas-phase refrigerant and liquid-phase refrigerant within the first compartment. After a predetermined amount of liquid-phase refrigerant accumulates in the first compartment, the liquid-phase refrigerant flows into the second compartment through the overflow pipe. Therefore, the proposed condenser has an excellent gas liquid separation performance.
However, the condenser disclosed in the publication has the following problem. When refrigerant is charged into a refrigeration cycle in which the condenser is used, after a predetermined amount of liquid-phase refrigerant accumulates in the first compartment, the liquid-phase refrigerant flows into the heat exchange tubes of the supercooling section through the second compartment, the refrigerant outflow hole, and the supercooling section inlet header. Therefore, the heat exchange tubes of the supercooling section cannot be filled with liquid-phase refrigerant at an early stage, and a relatively large amount of refrigerant must be charged to reach a stable region where the degree of supercooling becomes constant. Accordingly, a relatively large amount of refrigerant must be charged.